Glutathione-S-transferases are a ubiquitous family of enzymes involved in protection against oxidative damage and detoxification of cytotoxins. GSTs protect cells by catalyzing the transfer of electrophilic compounds to the thiol group of glutathione. Schistosomes contain two distinct GSTs; both of these enzymes have potential use as vaccines against schistosomiasis as they have been shown to induce a protective host immune response when injected into rodents. We have recently determined the structure of Schistosoma japonica using a combination of molecular replacement and isomorphous replacement techniques. We now intend to determine structures of S. japonica GST in complex with various glutathione analogs, toxins and inhibitors.